Machine for forming an elliptical open end on heat shrunk packages

ABSTRACT

Wrapping machine positions heat-shrinkable wrapper around package with underlapped side edges along the bottom of the package. A conveyor advances the package to a bottom sealer, with driven bottom belts holding underlap tight, to a heated sealer that fuses the lap. Backing rolls located at the sides of the conveyor are advanced into the open tubular ends of the wrapper as the package advances over the sealer, so that the sealer forms the wrapper in a complete tube from end to end. Backing rolls retract out of the tube and package is advanced to a heat shrink tunnel where the continuous tubular form of the ends of the wrapper cause it to shrink into an elliptical opening with the wrapper shrunk over all four edges of the ends of the package.

United States Patent [72] Inventors Ronald Holt;

Stanley J. Puskarz, both of Battle Creek, Mich. [2| 1 Appl. No. 840,628 [22] Filed July 10, 1969 [45] Patented June 22, 1971 [73] Assignee Battle Creek Packaging Machines, lnc. Battle Creek, Mich.

[541 MACHINE FOR FORMING AN ELLIPTICAL OPEN END 0N HEAT Sl'mUNK PACKAGES 4 Claims, 6 Drawing Figs.

[52] US. Cl 53/184, 53/210 [51] lnt.Ci B65b 11/10, v B65b 53/02 [50] Field of Search 53/209, 210, 379, 184

[56] References Cited UNITED STATES PATENTS 2,196,666 4/ 1940 Moore 53/379 X 2,634,564 4/1953 Bergstein 3,504,476 4/1970 Ehrenfriedetal.

Primary Examiner-Theron E. Condon Assistant Examiner-Neil Abrams Attorney-Austin A. Webb open tubular ends of the wrapper as the package advances over the sealer, so that the sealer forms the wrapper in a complete tube from end to end. Backing rolls retract out of the tube and package is advanced to a heat shrink tunnel where the continuous tubular form of the ends of the wrapper cause it toshrink into an elliptical opening with the wrapper shrunk over all four edges of the ends of the package.

PATENTEU JUN22 1971 SHEET 1 OF 3 m y z wm/ nJ/q wy/V ATTORNEY MACHINE FOR FORMING AN ELLIPTICAL OPEN END N HEAT SIIRUNK PACKAGES This machine is a variation of the wrapping machine shown in U.S. Pat. No. 3,276,184 to Holt.

The drawings, of which there are three sheets, illustrate a preferred form of the machine of the invention.

FIG. I is a side elevational view showing the general relationship between the parts of the machine of the invention.

FIG. 2 is an enlarged, fragmentary, cross-sectional view taken along the plane of the line 2-2 in FIG. 1 and showing the novel parts of the machine in plan.

FIG. 3 is an enlarged, fragmentary vertical cross sectional view taken along the plane of the line 3-3 in FIG. 2.

FIG. 4 is a fragmentary cross-sectional view taken along the plane of the line 4-4 in FIG. 2.

FIG. 5 is a diagrammatic, composite, view showing, in a plan view, the condition of the package and its wrapper as they advance through the machine.

FIG. 6 is a diagrammatic, composite, view showing the ends of part of the packages in FIG. 4.

Generally, the wrapping machine comprises a wrapper overfolding conveyor 10, a bottom sealer l2 and a heat shrink tunnel or oven 14. In the example illustrated, the packages or articles to be wrapped are indicated by the dotted lines at P-l, P-2 and P-3 located at different positions along the route through the machine. More specifically, the packages consist of pallets or low trays 16 of corrugated paperboard, with sidewalls l8. Wrapper sheets of heat shrinkable synthetic plastic sheet material are shown at 20, and a plurality of cans C are retained in the trays by the wrappers.

The overfolding conveyor is adapted to receive and support the leading sides of wrappers 20 and to further have the package P-l delivered onto the inlet end of the conveyor, and over the leading side of the wrapper. The weight of the package holds the wrapper on the conveyor and the conveyor advances the wrapper to the right as shown. Mechanism for delivering both the articles and the wrapper sheets is more particularly shown in the Holt patent referred to above, and is not illustrated. The overfolding conveyor includes a foldover bar 22 that is advanced through a complete circuit around each package as the package moves along the conveyor. In the example shown, side uprights 24 support sprockets 26 at the comers of the circuit, and a chain loop 28 on each side of the conveyor supports the ends of the fold over bar. The lower right sprockets 26 are driven as by the chain 30 from a main drive shaft 32, so that the bar moves upwardly behind the trailing side of package P-l, and in so doing picks up the trailing portion of the wrapper sheet and folds it forwardly and downwardly along the leading side of the package before the leading side of the package travels beyond the right or off-feed end of conveyor. Shaft 32 also drives the belt of conveyor 10 by a chain 34.

The bottom sealer 12 includes a support plate 36 with a package receiving left edge 38 that intercepts the overfolded side of the wrapper as the wrapper hangs across the leading side of the package and folds it back into underlapped relation to the initial leading side of the wrapper as at 40 (see FIGS. 5 and 6). As the package is advanced ofi of the conveyor 10, forward moving force is taken over by an overhead conveyor 42. Conveyor 42 has a pusher flight bar 44 supported by chains 46 trained around sprockets 48. One sprocket 48 is driven by chain 50 from shaft 32.

With particular reference to FIGS. 2 and 4, it will be seen that plate 36 has several slots 52 distributed across its width. A plurality of belts 54 are supported with their upper sides pro jecting through the plate 36 and supported by the pulleys 56 and 58. The pulleys 58, on a shaft 60 are driven by a chain 62 from the shaft 64 which is in turn driven from the sprocket 66 to advance the belts at the same speed as the flight bar 44. This prevents the friction of the plate 36 on the bottom of the package from sliding the underlapped portion 40 of the wrapper rearwardly on the package. The belts 54 further keep the wrapper tight around the package as the forward motion of the belts acting on the initially leading, bottom portion of the wrapper prevents this part of the wrapper from being pulled out and away from the underlap 40 by friction drag on plate 36.

A bottom sealer roll 68 extends across the plate closely ad- 5 jacent to the ends of the belts 54. The roll has lobes 70 that project upwardly through openings 72 in the plate into heatsealing contact with the underlap 40 of the wrapper. The sealer roll is electrically heated by means that have not been illustrated as such construction is well known. The roll is driven by an intermediate gear 74 from a gear 76 on shaft 78. The shaft 78 is driven by chain 80 from the main shaft 32, and incidentally passes over sprocket 66 to drive shaft 64 and the belts 54.

After passing the bottom sealer roll, the packages are picked up by chains 82 of a conveyor 84 that advances the packages through the heat shrink tunnel or oven 14. The chains 82 are driven by sprockets on the shaft 78.

Positioned over the ends of the bottom sealer roll 68, at each side of the bottom sealer, is a bottom seal extension roll 86. Each roll is freely rotatable about a stub shaft 88 and the shaft is in turn reciprocably supported in bearings 90 on a bracket 92. The bracket is secured to an edge of the upright side plate 94, that carried the overhead conveyor 42. Also supported on the bracket 92 is a transversely extending pressure cylinder 96 with a piston rod 98. The rod of the cylinder,

on each side of the machine, is connected by a plate 100 to the adjacent shaft 88 to reciprocate the latter. The pressure cylinders are actuated by pressure connections (not illustrated) under the control of a cam operated valve conventionally illustrated at 102 in FIG. 2 and driven by the main drive shaft 32. The cam and valve are arranged or timed to extend the piston rods and project the seal extension rolls into the tubular extension of wrapper at eachv end of the package, as soon as the leading side of the package passes the roll. The roll, which has a chamfered inner end 104, thus rolls in opposed relation to the end lobes 70 on the bottom sealer roll. This forms secure seals 106 in the ends of the overlapped portion 40 on the bottom of the package (See FIG. 5). After the seals 106 are formed, the valve 102 retracts the extension roll to clear the trailing side of the tubular wrapper.

The function of the end seals 106, and the purpose of the extension rolls 86, is shown in FIGS. 5 and 6. The wrapper material 20 begins to shrink when subject to heat and this shrinkage is unifonn in all directions, so the tubular ends of the wrapper first contract into a tapered or semiconical shape as at 108. The seals 106 of the bottom underlap prevent the comers of the wrapper from shrinking away from each other. The final shrinking process causes the tubular end extension to collapse into a tight, flat end wall with an elliptical hole 110 in the center. The end walls of the packing tray 16 and the end articles C are thus firmly held together; rather than having the comers of the wrapper shrunk away from each other leaving a ragged and weak gap at the ends of the bottom of the wrapper.

What we claim as new is:

l. A wrapping machine having means for receiving and advancing a package with a wrapper of heat shrinkable material arranged in tubular form around the package with an overlap between the sides of the wrapper and tubelike extensions at each transverse end of the package,

a transversely extending sealer arranged to act upon the overlap of the wrapper and package bottom as the package is advanced thereover, and extending beyond the ends of the package,

means rotatably mounting extension rolls in transversely extending relation at both sides of said package advancing means,

means arranged to transversely reciprocate said rolls into said tubelike extensions of the wrappers and into opposed coacting relation with the ends of said sealer and in timed relation to the sealer, as the package advances,

and means located at the outlet end of said package advancing means for applying heat to said wrapper to shrink the wrapper, after said extension rolls and sealer have sealed the ends of the wrapper.

movable in the same direction as the package to hold said underlapped edges in position,

said belts being located between the edge of said fixed surface and said transversely extending sealer.

3. A wrapping machine as defined in claim 2 in which said belts are driven at about the same speed as said package advancing means.

4. A wrapping machine as defined in claim 3 in which said extension rolls have tapers on their transversely inner ends. 

1. A wrapping machine having means for receiving and advancing a package with a wrapper of heat shrinkable material arranged in tubular form around the package with an overlap between the sides of the wrapper and tubelike extensions at each transverse end of the package, a transversely extending sealer arranged to act upon the overlap of the wrapper and package bottom as the package is advanced thereover, and extending beyond the ends of the package, means rotatably mounting extension rolls in transversely extending relation at both sides of said package advancing means, means arranged to transversely reciprocate said rolls into said tubelike extensions of the wrappers and into opposed coacting relation with the ends of said sealer and in timed relation to the sealer, as the package advances, and means located at the outlet end of said package advancing means for applying heat to said wrapper to shrink the wrapper, after said extension rolls and sealer have sealed the ends of the wrapper.
 2. A wrapping machine as defined in claim 1 in which said package advancing means includes a section for advancing the package in retaining engagement on top of the leading side of the wrapper, and overfolding the trailing portion of the wrapper over and downwardly across the leading side of the package, a fixed surface arranged to direct the overfolded side of the wrapper into underlapped relation to the bottom of the package and the leading side edge of the wrapper, and wrapper retaining belts set into said fixed surface and movable in the same direction as the package to hold said underlapped edges in position, said belts being located between the edge of said fixed surface and said transversely extending sealer.
 3. A wrapping machine as defined in claim 2 in which said belts are driven at about the same speed as said package advancing means.
 4. A wrapping machine as defined in claim 3 in which said extension rolls have tapers on their transversely inner ends. 